150 / 2018-08-25 15:39:34

The Effect of Free Curing Agent Diffusion on Mechanical Properties of Epoxy System

Free curing agent; Diffusion; Epoxy system; Mechanical properties

Curing agent as an indispensable component of epoxy system, it acts to link the epoxy resin molecular chains to form a three-dimensional network structure. Because of the different crosslinking densities between curing agent and epoxy resin, there will be free curing agent, which will diffuse in epoxy system. In this paper, bisphenol A epoxy resin was crosslinked with tetrahydrophthalic anhydride curing agent to obtain epoxy systems with different crosslinking densities. The diffusion strength of free curing agent and the mechanical properties of epoxy systems were studied by molecular dynamics. The results show that with the increase of crosslinking density, the mean square displacement and linearity of free curing agent in epoxy system decrease. With the increase of temperature, the mean square displacement of free curing agent in epoxy system increases. In the epoxy system with high crosslinking density, the temperature at which the mean square displacement of free curing agent change significantly is increasing. Young's modulus and shear modulus increase with the increase of crosslinking density of epoxy system, and decrease with the increase of temperature. The diffusion of free curing agent is related to the mechanical properties of epoxy system. The stronger the diffusion of free curing agent, the worse the mechanical properties of epoxy system.